Purification of milk peptides using integrated membrane processes

牛乳蛋白是目前公认的具有抗高血压、免疫调节、脂质和矿物质结合、抗菌等生物活性肽的来源。这些所谓的生物活性肽越来越多地被用作食品系统中的保健成分或补充剂。生物活性肽具有不同的电荷（阳离子、阴离子、中性）和分子量（500-2000 Da），可以通过酶水解产生。与生产生物活性肽相关的主要问题是找到一种从复杂混合物中纯化它们以提高其效力的方法。本研究是基于这样的假设，即以大小、电荷和溶解度为分离参数的膜工艺可以成功地从复杂混合物中纯化肽（>95%）。这项工作的目的是开发一种基于膜的纯化程序，从牛奶中提取阳离子、阴离子和中性肽。该项目的目标将是：(1)评估不同商业上可用于从复杂混合物中分离酸性肽的NF膜材料的潜力；(2)表征聚电解质（多糖）的存在对b-LG多肽混合物和NF组分中溶解度、二级结构和肽-肽相互作用的影响；(3)表征b-LG肽结合谱对NF分离选择性的影响；(4)验证将NF和预处理与复杂系统（如全脂牛奶或乳清蛋白水解物）相结合的分离方法。这项研究将提供前所未有的机会，以更好地了解肽从复杂混合物的分离，并将知识应用于其他肽，如生长因子，天然存在于牛奶中。

Bovine milk proteins are now recognized as a source of peptides having biological activities such as antihypertensive, immunomodulating, lipid and mineral-binding ant antimicrobial. These so-called bioactive peptides are increasingly used as health ingredients in food systems or as supplements. The bioactive peptides are characterized by different charge (cationic, anionic, neutral) and molecular weight values (500-2000 Da) can be produced by enzymatic hydrolysis. The main problem associated with the production of bioactive peptides is to find a process to purify them from a complex mixture in order to increase their potency. The present work is based on the hypothesis that a membrane-based process integrating size, charge and solubility as separation parameters can successfully achieve the purification (>95%) of peptides from complex mixture. The aim of the work is to develop a membrane-based purification procedure for cationic, anionic and neutral peptides from milk. The objectives of the project will be to (1) Evaluate the potential of the different NF membrane materials commercially available for the separation of acidic peptides from complex mixtures; (2) Characterize the effect of the presence of polyelectrolytes (polysaccharides) on solubility, secondary structure and peptide-peptide interactions in b-LG peptide mixtures and NF fractions;(3) Characterize the binding profile of b-LG peptides on the selectivity of NF separations; (4) Validate a separation approach combining NF and pre-treatments with complex systems such as complete milk or whey protein hydrolysates. This research will provide un-precedent opportunities to better understand the separation of peptides from complex mixtures and to apply the knowledge to other peptides, such as growth factors, naturally-occurring in milk.